北美海蓬子胆碱单加氧酶基因CMO的克隆及表达研究

Cloning and Expression Analysis of Choline Monooxygenase(CMO) Gene in Salicornia Bigelovii Torr.

胆碱单加氧酶(CMO)是合成植物小分子非毒性有机渗透调节物质甜菜碱过程中重要的限速酶.文中采用RACE技术以北美海蓬子为实验材料克隆CMO基因的全长c DNA序列(Genbank登录号:KM884944),并做相关的生物信息学分析.研究结果表明,该基因c DNA全长1 834 bp,其中开放阅读框(ORF)有1 317 bp,编码439个氨基酸,预测其蛋白分子量为49.537 k Da,理论等电点(p I)为6.15;序列分析显示北美海蓬子CMO蛋白中含有2个重要的保守域和功能域,不存在跨膜区域;除了与蒺藜苜蓿及水稻的同源性分别为46%和49%外,与其他植物CMO蛋白序列相似性均达到55%以上;系统进化树分析显示,它与欧洲海蓬子的亲缘关系最近;实时荧光定量PCR结果显示,随着Na Cl浓度的升高,北美海蓬子CMO基因的表达量增加,说明该基因可通过盐胁迫诱导表达.

Choline monooxygenase （CMO） is one of the key enzymes involved in the Glycine betaine （GB） biosynthesis pathway. In this study, CMO gene （GenBank accession No. KM884944） complete eDNA length is cloned from Salicornia Bigelovii Torr. based on RACE technology, and characterized for the sequence in terms of bioinformation by various software packages. The eDNA is comprised of 1834 bp, containing a 1317 bp ORF which encodes 439 amio acid residues with a predicted molecular mass of 49.537 kDa and theoretical pI of 6.15. The Salicornia Bigelovii Torr. CMO protein shares more than 50% amino acid sequence similarity with that of other plants except Medicago truncatula （46%） and Oryza sativa Japonica （49%）. It contains two consensus domains and two functional domains. There is no transmembrane domain. The phylogenetic tree analysis indicates that CMO has the closest genetic relationship with Salicornia europaea. Real-time quantitative PCR reveals that the expressions of Salicornia Bigelovii Tort. CMO gene is up-regulated by NaCI. The results demonstrate that CMO gene expression ofSalicornia Bigelovii Tort. can be induced by NaCl stress.